Field of the Invention
The present invention generally relates to medical devices, and more specifically relates to medical devices used for extracting tissue.
Description of the Related Art
There have been many efforts directed to tissue extraction devices. For example, commonly assigned U.S. Pat. No. 5,458,598 teaches a cutting and coagulating forceps tool having a housing with a protruding barrel, a pair of electrocautery jaws that are closed by camming contact with the mouth of the barrel when the jaws are retracted, and an independently sliding cutting blade that passes between the jaws. The jaws are opened by squeezing a trigger, and the cutting blade is advanced by pressing a lever with the thumb. In use, tissue is grasped between the jaws by first squeezing the trigger to open the jaws, then advancing the jaws over the tissue and releasing the trigger. The torsion spring pulls the jaws back into the mouth of the barrel, whose camming action drives the jaws together, clamping the tissue. Depending upon the thickness of the tissue, the jaws remain partially open a greater or lesser amount. A surgeon may depress a foot pedal to pass a high frequency voltage across the jaws to coagulate the tissue. An electrocauterization procedure destroys tissue using heat conduction from a metal probe that is heated by an electric current. The procedure is used for cutting through soft tissue and to stop bleeding. When the tissue has been sufficiently coagulated, the foot pedal is released, and the blade is advanced by pressing one of the thumb levers forward. When the thumb lever is released, the tension spring retracts the blade, and the tissue is released by squeezing the trigger.
Commonly assigned U.S. Pat. No. 5,520,634 discloses a mechanical morcellator that provides for the removal of tissue without requiring large entry incisions. The mechanical morcellator is adapted to be inserted through a laparoscopic port site and directly fragment and aspirate tissue from within a patient's body. The mechanical morcellator includes a rotatable and retractable cutting head. User manipulation varies the amount the cutting head extends out of a sheath, the amount of suction communicated to the cutting head, and the operation of a motor which rotatably drives the cutting head. Suction is communicated to the cutting head to aspirate the tissue fragmented by the cutting head.
Tissue extraction is often necessary to treat Benign prostatic hyperplasia (BPH), which is a condition involving an increase in the size of the prostate in middle-aged and elderly men. BPH is characterized by hyperplasia of prostatic stromal and epithelial cells, resulting in the formation of large, fairly discrete nodules in the periurethral region of the prostate. When sufficiently large, the nodules compress the urethral canal to cause partial, or sometimes complete, obstruction of the urethra, which interferes with the normal flow of urine. BPH also leads to symptoms of urinary hesitancy, frequent urination, dysuria (painful urination), increased risk of urinary tract infections, and urinary retention.
BPH symptoms generally fall into two categories: storage and voiding. Storage symptoms include urinary frequency, urgency (compelling need to void that cannot be deferred), urgency incontinence, and voiding at night (nocturia). Voiding symptoms include weak urinary stream, hesitancy (needing to wait for the stream to begin), intermittency (when the stream starts and stops intermittently), straining to void, and dribbling.
If left untreated, BPH symptoms can worsen. Incomplete voiding typically results in stasis of bacteria in the bladder residue and an increased risk of urinary tract infection. Urinary bladder stones may form from the crystallization of salts in the residual urine. Urinary retention is another form of progression. Acute urinary retention is the inability to void, while in chronic urinary retention the residual urinary volume gradually increases, and the bladder distends. Some patients that suffer from chronic urinary retention may eventually progress to renal failure (e.g., obstructive uropathy).
Many therapies have been developed for treating BPH. These therapies are generally broken down into two groups: minimally invasive treatments (thermotherapy) and surgical treatments. Minimally invasive treatments, which rely on the absorption of necrosed tissue over time to alleviate symptoms, include laser (e.g., non-contact, contact, interstitial types), microwave (e.g., TUMT), and thermotherapies (e.g., Prostiva™ RF therapy). Surgical treatments include transurethral resection of the prostate (TURP), holium laser enucleation of the prostate (HoLEP), transurethral incision of the prostate (TUIP), and transurethral ultrasound-guided laser incision of the prostate (TULIP).
Most of the above-described treatments involve a urethral approach whereby a large bore cystoscope is used to visualize and remove benign tissue. The urethral approach is rather invasive and causes an inflammatory response that restricts the flow of urine and results in the need for a catheter. These treatments also have serious side effects such as retrograde ejaculation (up to 90% in some procedures), impotence and bleeding.
The two most common types of office-based therapies for BPH are Transurethral Microwave Thermotherapy (TUMT) and TransUrethral Needle Ablation (TUNA). Both of these procedures involve delivering enough energy to create sufficient heat to cause cell necrosis in the prostate. The goal of the therapies is to cause sufficient necrosis so that the dead tissue is reabsorbed by the body to shrink the prostate and relieve the obstruction of the urethra. These procedures are typically performed with local anesthesia, and the patient returns home the same day. Common problems after TUMT include inability to urinate and having to use a catheter for a week or more. Urinary retention happens in about 8 in 100 men who have this treatment. Other side effects include blood mixed in with the urine or sperm. Sexual problems also occur whereby about one in three men who have the TUMT procedure have problems then they ejaculate or have blood in their semen. The TUNA procedure is less effective than traditional prostate surgery (e.g., TURP). Side effects include blood in the urine for several days after the procedure, painful urination, or the need for a catheter after surgery.
Transurethral resection of the prostate (TURP) is a broadly used surgical procedure that requires general anesthesia and the insertion of a resectoscope through the urethra and into the prostate. During the TURP procedure, which lasts about 90 minutes, obstructing portions of the prostate are removed using an electric loop. After the TURP procedure is completed, the patient is usually required to stay in the hospital for about one to four days, and use a catheter for about one to three days. Complete recovery takes about four to six weeks. Common side effects include retrograde ejaculation, impotence and bleeding.
During tissue removal procedures, it is desirable to limit the invasiveness of the procedure so as to minimize the trauma experienced by the patient. In modern surgery, access to a surgical site is often provided by using one or more trocars and cannulas that are inserted into tissue. A visualization system is used to identify the target tissue to be removed as well as locate the surgical instruments. However, the entry incision must still be sized to allow for the removal of the severed tissue and, therefore, the reduction in entry incision size is rather limited, even in more or recently developed surgical procedures.
Thus, there remains a need for a minimally invasive benign prostatic hyperplasia device that does not use a transurethral approach to treat BPH. There also remains a need for a minimally invasive medical device for treating BPH that significantly reduces side effect such as retrograde ejaculation, impotence and bleeding. There also remains a need for a minimally invasive medical device for treating BPH that avoids the needs for using a catheter for voiding after the procedure. There also remains a need for a medical device that enables BPH procedures to be performed in an office setting, an ambulatory center, or a surgical suite without requiring hospitalization or an extended hospitalization stay. There also remains a need for a medical device for treating BPH that does not require significant additional capital expenditures. There also remains a need for a BPH medical device that enables for precise core samples of tissue to be removed and that enables the device to reach a target tissue location with less patient trauma. In addition, there is a need for a device used for biopsies that enables tissue samples to be cored and extracted for analysis.